The west London club revealed Monday that Luiz is not a part of the 21-man squad for the trip to Switzerland as he requires on-going treatment on the bruised patella that saw him miss Saturday's 3-0 win at West Ham.

But manager Jose Mourinho is boosted ahead of the Group E clash by the return to fitness of club-record signing Fernando Torres.

The former Liverpool striker has been sidelined since the start of the month with an adductor muscle problem and will be targeting a comeback in Tueday's fixture, in which a win for Chelsea would be its fourth successive victory in the Champions League.

The Blues only require a point against the Swiss champions to ensure qualification to the round of 16, but Mourinho will be taking nothing for granted after Basel's shock 2-1 victory at Stamford Bridge when the sides met in September.

Chelsea won 2-1 in its last trip to St. Jakob-Park in last season's Europa League semifinal, when a David Luiz free kick settled matters in the closing minutes.